Magnetic Particle Imaging (MPI) Guided Magnetic Hyperthermia Therapy

Zhi Wei Tay et al. describe in the newest ACS Nano article how the labs of Steven Connolly and Carlos Rinaldi combined MPI and Magnetic Hyperthermia and tested successfully a theranostic platform for future cancer therapy. They showed experimental data using MPI gradients to deliver targeted heating on demand to components of a phantom with an ability to selectively heat targets separated by as little as 7 mm with negligible heating of off-target sites. Results from a rodent model are very promising.
MPI seems to be an excellent tool for thermal dose planning via an MPI pre-scan. Through a luciferase assay and histological assessment, they verified that heat damage was indeed localized to the target tumor. They further describe that an important next step is to develop MPI thermometry for in vivo implementation in order to provide a temperature feedback mechanism for complete thermal dose control.
Because achieving macroscopic heating with low amplitudes remains a challenge, another important direction is to explore MPI-magnetic hyperthermia for applications in targeted drug release by using the MPI gradient localization strategy to localize actuation of the drug-containing nanocarriers. Exploring other therapeutic approaches that do not require macroscopic temperature changes, such as activation of lysosomal pathways and thermal drug delivery, are also of great interest.

To read more, check out this link.

New Toyota Magnet Cuts Rare-Earth Use

The rise of electric vehicles is threatening supplies of a host of the earth’s elements. Cobalt and lithium for batteries are getting most of the attention, but rare earths for electric motors are also a pinch point. Now, Toyota Motor scientists have developed a new recipe for the motors’ permanent magnets that cuts reliance on particularly rare rare earths.

Permanent magnets keep electric motors turning in all kinds of devices, from electric toothbrushes to refrigerator compressors. In electric vehicles, the magnets need to last a long time without demagnetizing. They also have to stay stable at temperatures that can reach 100 ºC. To meet those requirements, the magnets are made up of 30% rare earths, to take advantage of their many unpaired electrons, and 70% iron. The go-to rare earth for powerful, durable magnets is neodymium.

Most of this pricey element comes from China, and Toyota says demand is expected to increase rapidly. Smaller amounts of terbium or dysprosium are added to neodymium to lend heat resistance, but those elements are even more expensive. Toyota has already cut terbium and dysprosium use in the 2016 Prius, and future magnets won’t use any, the firm promises. In addition, up to 50% of the neodymium will be replaced with the low-cost rare earths lanthanum and cerium.

To make the new recipe work, Toyota scientists reduced the size of the magnet’s grains to 0.25 micrometers, one-tenth their original size. They then concentrated neodymium on the surfaces of the smaller grains; the grains in standard magnets have the expensive element throughout. Looking inside the grains, they found that a 1:3 ratio of lanthanum to cerium is needed to prevent magnet performance from deteriorating.

Toyota says the new magnets could reach the market in the first half of the 2020s. They could also be used in robots and household appliances.

Iron Salts Produce Beautiful Crystal Landscape

Alexis Ostrowski's lab at Bowling Green State University studies reactions of iron salts, where iron (III) is reduced by light. Sometimes, the results are spectacular, like in this petri dish, where Fe(III) ammonium citrate (green) and potassium ferricyanide (orange and yellow) turn into  blue Fe(II) salts, like Prussian Blue etc.

Using Nature's Motors to Deliver Drugs

In a recent C&EN article, it was mentioned that bacteria and sperm have natural advantages over synthetic nanomotors when navigating the body’s byways. And as an example for how to exploit that they gave the example of how Sylvain Martel at the Polytechnique Montreal used a strain of Magnetococcus marinus bacteria called MC-1 to carry anticancer drugs into tumors within mice (Nat. Nanotechnol. 2016, DOI: 10.1038/nnano.2016.137). This bacteria species is a good choice for entering tumors, he says, because it likes a low-oxygen environment, which is typically found in tumors.

Martel’s team created the swimmers by covering individual MC-1 bacterial cells with over 70 nanosized liposomes containing anticancer drugs. This keeps the overall size of the swimmers under 2 µm, small enough to enter and move around within tumors, Martel says. The researchers tested the swimmers in mice that had colorectal tumors by injecting the swimmers a few millimeters outside the tumors, magnetically guiding the swimmers into the tumors, and then letting them penetrate deep inside. Up to 55% of the injected swimmers entered the tumors, concentrating around regions with particularly low oxygen levels.

Combination of MPI and MFH

Steve Conolly and his group together with Carlos Rinaldi and his group have just published an interesting article about combining magnetic fluid hyperthermia (MFH) and magnetic particle imaging (MPI). The physics germane to and exploited by MPI and MFH are similar, and the same magnetic particles can be used effectively for both. Consequently, the method of signal localization through the use of gradient fields in MPI can also be used to spatially localize MFH, allowing for spatially selective heating deep in the body and generally providing greater control and flexibility in MFH. Furthermore, MPI and MFH may be integrated together in a single device for simultaneous MPI-MFH and seamless switching between imaging and therapeutic modes.

The authors show simulation and experimental work quantifying the extent of spatial localization of MFH using MPI systems. They report the first combined MPI-MFH system and demonstrate on-demand selective heating of nanoparticle samples separated by only 3 mm (up to 0.4 °C per second heating rates and 150 W/g SAR deposition). They also show experimental data for MPI performed at a typical MFH frequency and show preliminary simultaneous MPI-MFH experimental data.

Check the paper out here.

Iron-Oxide Nanoparticle-Based Magnetic Resonance Contrast Agents

If you ever needed to know all about magnetic nanoparticles as MRI contrast agents, then you have it now all in one place. A large group of authors just published a comprehensive review of this field as chapter 4 of of the book "New Developments in NMR No. 13, Contrast Agents for MRI: Experimental Methods", Edited by Valerie C. Pierre and Matthew J. Allen, The Royal Society of Chemistry 2018.

If you can't find it in your library, then please contact Ladislau Vekas, he can help you out.

Fast Magnetic Data Storage

Magnetic data storage has long been considered too slow for use in the working memories of computers. Researchers at ETH have now investigated a technique by which magnetic data writing can be done considerably faster and using less energy. Instead of using a current-carrying coil producing a magnetic field to change the direction of magnetization they used an electric current passing through a specially coated semiconductor film. They found that the magnetization inversion happened in less than one nanosecond – considerably faster than in other recently studied techniques. In a first step, the researchers would now like to optimize their materials in order to make the inversion work even faster and at smaller currents.

Frontiers in Biomagnetic Particles Meeting 2017 - Excellent as Always!

The 2017 meeting in Asheville, NC, was a great success. This would not be possible without the outstanding talks, posters, and discussions that you can go and check out in the attached abstract booklet here. But it also would not be possible without the energy of the organizers, Jennifer Andrew, Mark Bolding, Thompson Mefford, to again find a great meeting location, excellent invited speakers, and allow for pleasant information exchange and a chance for a good time together. Thank you all!

For more information, check out this website.